1. Field of the Invention
The present invention relates to a funnel for slim cathode ray tubes, and, more particularly, to a funnel for color cathode ray tubes constructed such that stress is prevented from being concentrated on the funnel when a deflection angle is 110 degrees or more.
2. Description of the Related Art
FIG. 1 is a side view, partially cut away, illustrating a conventional cathode ray tube. As shown in FIG. 1, the conventional cathode ray tube comprises a panel 1 and a funnel 2, which are joined with each other to constitute a tube part 10.
Inside the panel 1 is disposed a shadow mask 3, which is supported by a frame 4 such that the shadow mask 3 is approximately parallel with the panel 1. The frame 4 is fixed to the panel 1 via a spring 5. Inside the funnel 2 is disposed an inner shield 6 for shielding an external geomagnetic field to prevent the path of an electron beam from being curved by the external geomagnetic field.
In the rear part of the funnel 2 is fitted an electron gun 7 for generating an electron beam. At the outside of a neck part of the funnel 2 is mounted a deflection yoke 8 for deflecting an electron beam approximately 110 degrees or less.
In the conventional cathode ray tube with the above-stated construction, an electron beam emitted from the electron gun 7 is deflected above and below and right and left by the deflection yoke 8, and is then transmitted to the panel 1. Specifically, the deflected electron beam passes through-holes of the shadow mask 3, and is then transmitted to a fluorescent screen 9 coated on the inner surface of the panel 1. At this time, the fluorescent screen 9 is illuminated by the energy of the electron beam. Consequently, a picture is reproduced such that users can see the picture reproduced through the panel 1.
Meanwhile, the panel 1 and the funnel 2 are joined to each other by a frit sealing process, the electron gun 7 is fitted into the rear part of the funnel 2 by a subsequent encapsulation process, and a vacuum is formed in the tube part 10 by an extraction process. In this way, the cathode ray tube is manufactured.
When the tube part 10 is in the vacuum state, considerable tensile and compression stresses are applied to the panel 1 and the funnel 2.
FIG. 2 is a front view illustrating the funnel of the conventional cathode ray tube, and FIG. 3 is a side view illustrating the funnel of the conventional cathode ray tube. In the past, a yoke part 2y of the funnel 2 was formed in a circular structure. Recently, however, the yoke part 2y of the funnel 2 has been changed into a rectangular structure to increase deflection sensitivity of the deflection yoke. In the case of the rectangular-structure yoke part 2y, it is designed such that an angle of approximately 20 degrees or more is maintained at a top of round (TOR) part of the funnel 2 toward the panel 1.
In the conventional color cathode ray tube, the deflection angle of which is 110 degrees or less, the stress applied to a body 2b of the funnel 2 is less than that applied to the panel 1. Consequently, the stress applied to the body 2b of the funnel 2 does not have a great influence on an explosion-resistance test, which is an endurance test based on external impact.
However, the overall length of the tube part 10 is decreased with the development of a slim color cathode ray tube, and therefore, it is inevitable that the lengths of the panel 1 and the funnel 2 be decreased. As a result, the inner volume of the tube part 10 is also reduced. Consequently, stress applied to the panel 1 and the funnel 2 is increased.
Especially in the case of the funnel 2, it is structurally difficult to reduce the length of the yoke part 2y, at which the deflection yoke is mounted. For this reason, the length of the body 2b is generally reduced to decrease the overall length of the funnel 2. However, due to the reduction in length of the body 2b of the funnel 2, stress is concentrated at the TOR part, where the body 2b and the yoke part 2y are connected to each other. As a result, the explosion-resistance characteristic on the external impact is lowered.
Consequently, it is required that stress be prevented from being concentrated at the part where the body 2b and the yoke part 2y of the funnel 2 is connected although the length of the part at which the body 2b and the yoke part 2y of the funnel 2 is connected is reduced.